1. Field of the Invention
The present invention relates to a data processing terminal, and more particularly, to a hand-held data processing terminal to be connected to an optional external device.
2. Description of the Related Art
Recently, hand-held data processing terminals have been used to collect data at the point of generation of the data, to order commodities and to manage stocks. The terminals are used in various industries, such as the distribution, manufacturing, power, gas, and water industries, to enable operators to enter and process data at a point of generation of the data that may be outdoors or indoors.
The data collected by the terminals are transferred to a personal computer or a server, which analyzes and processes the data, to make decisions on business plans and customer service.
One of the data input techniques usually adopted by the terminals is to read bar codes. Compared with manually entering data through a keyboard, reading bar codes is simple and fast and involves less errors.
The bar codes are read by a pen scanner, a touch scanner, or a laser scanner connected to the terminal, and bar code data are transferred to the terminal.
By the way, control command systems for bar code readers, including pen scanners, touch scanners, and laser scanners, differ from one another depending on their types. If a control command system in a given hand-held data processing terminal is entirely different from that of the bar code reader connected to the terminal, the bar code reader may not work. Moreover, if the command system in the terminal is connected to the wrong bar code reader, it may damage the bar code reader.
This trouble will not happen if all bar code readers employ the same command system. This, however, is not practical because it costs a large amount of money to remodel bar code readers. It is more economical to use marketed bar code readers. The problems of the related art will be explained in detail later.
An object of the present invention is to provide a hand-held data processing terminal capable of determining the type of an external device such as a bar code reader connected thereto and converting a control command in a predetermined format into one in another format, to enable the terminal to employ a single program to control bar code readers of different command systems. Another object of the present invention is to provide a compact, low power consumption, convenient hand-held data processing terminal.
According to the present invention, there is provided a data processing terminal that sends control commands to an external device connected thereto, to control the external device, wherein the data processing terminal comprises a control command sending unit for sending a control command to the external device, and an external device determining unit for determining a type of the external device according to a response returned by the external device in response to the control command.
The data processing terminal may further comprise a determination result storing unit for storing a result of determination made by the external device determining unit. The determination result storing unit may be a volatile memory.
The data processing terminal may further comprise a control command converting unit for converting the control command in one format into one in a proper format for the external device according to a result of determination made by the external device determining unit and for sending the converted control command to the external device. The control command converting unit may carry out a command conversion for the control command according to a conversion table. The conversion table may be stored in a semiconductor memory.
The semiconductor memory may be a nonvolatile memory. The control command sent by the control command sending means may be a command not influencing to a reading operation of the bar code reader.
According to the present invention, there is also provided an external device connected to a data processing terminal and returning a response signal to the data processing terminal after receiving a control command from the data processing terminal, wherein the external device comprises a power source unit for supplying power to specific elements in the external device; a power supply control unit for stopping the power from the power source unit to the specific elements in the external device if another control command from the data processing terminal is not received within a predetermined time; and a timer unit, provided in the power supply control unit, for starting time-counting after receiving the control command from the data processing terminal, and the predetermined time being counted by the timer unit.
Further, according to the present invention, there is provided an external device connected to a data processing terminal and returning a response signal to the data processing terminal after receiving a control command from the data processing terminal, wherein the external device comprises a power source unit for supplying power to specific elements in the external device; a power supply control unit for stopping the power from the power source unit to the specific elements in the external device if another control command from the data processing terminal is not received within a predetermined time; and a timer unit, provided in the power supply control unit, for starting time-counting after returning the response signal to the data processing terminal, and the predetermined time being counted by the timer unit.
A state of stopping the supply of power to the specific elements may establishe a power saving state. The power supply control unit may comprise a trigger switch for activating a power source circuit and for supplying power to the specific elements in order to start reading a bar code, when the trigger switch is pushed during the power saving state.
The power supply control unit may comprise a polarity inversion detector for activating a power source circuit and for supplying power to the specific elements in order to start reading a bar code, when a proper command is sent from the data processing terminal during the power saving state. The polarity inversion detector may detect a polarity of the proper command and control to supply or stop the supply of power to the specific elements.
The external device may further comprise a controller for recognizing the control command and for carrying out an operation corresponding to the control command by using the specific elements.
The specific elements may include a light emitter for emitting a light to a bar code, a light receiving unit for receiving a reflected light from the bar code, and a decoder for decoding output signals of the light receiving unit in response to the reflected light.
The external device may be a bar code reader, and the data processing terminal may be a hand-held data processing terminal.